was replicated in the Irish Affected Sib Pair Study for Alcohol Dependence [Kendler et al., 2006a]. Further analysis of a subset of the COGA pedigrees on whom genome-wide SNP linkage data were produced for the Genetic Analysis Workshop 14 (GAW14) [Edenberg et al., 2005] suggested that the chromosome 2 linkage finding for alcohol dependence was one of the most robust linkage signals in the sample [Doan et al., 2005; Wang et al., 2005; Wiener et al., 2005]. Extension of the linkage markers available at the ends of the chromosomes in the GAW14 SNP set also suggested evidence for linkage peaks with alcohol dependence at the p and q ends of the chromosome, in addition to the primary centromeric linkage peak discussed here [Wang et al., 2005; Wiener et al., 2005; Agrawal et al., 2008]. Linkages to alcohol dependence [Wilhelmsen et al., 2005] and the related traits of alcohol withdrawal [Kuo et al., 2006] and smoking [Straub et al., 1999; Goode et al., 2003] have also been reported on chromosome 2 in independent samples. Although linkage to a comorbid habitual smoking and alcohol dependence phenotype has been reported to chromosome 2p in COGA [Bierut et al., 2004], the finding is largely
